Glutamine synthetase is known to be important in the metabolism of M. tuberculosis, the organism that causes tuberculosis. Tuberculosis kills more people (about 3,000,000/year) than any other preventable disease, and is increasingly resistent to antibiotics. Because of the importance of GS to its metabolism, and because of the difference of mammalian and bacterial GSs, GS is a logical target for anti-tuberculosis drugs. A high resolution structure for bacterial GS is important for rational drug design. Understanding the mechanism of inhibition of GS 12 could be helpful.